The invention relates to a method for separating products mounted on a common substrate from each other along (a) cutting line(s), which products each comprise one or more chips present on said substrate and connecting means connected thereto, the connecting ends remote from the chip of which are intended for connecting purposes.
A method for manufacturing such products is for example disclosed in European patent application EP-A-0 885 683. A large number of chips and associated connecting means, such as connection wires and solder balls which may be bonded to the connecting ends, are thereby present on a substrate. The products, which each comprise one or more chips and connection wires or the like connected thereto as well as solder balls which may be bonded to the connecting ends of said wires, must be separated from each other. In the case of larger products, the associated chip(s) may each be separately encapsulated, whilst in the case of smaller products a large number of chips associated with several products may be jointly encapsulated.
The substrate and, if present, possibly also the layer of material encapsulating the chips must be cut or sawn through for separating the products from each other.
With conventional methods, the joined products are mounted to a substrate and subsequently said substrate and possibly the layer of material encapsulating the chips are cut through. One drawback of the method that has been used so far is the fact that it is difficult to cool the saw blade or the like, since access to the saw blade is only possible from one side of the products. Another drawback is the fact that contamination with saw-dust of the products occurs, which makes it necessary to subject the products to a time-consuming and expensive cleaning treatment after they have been separated from each other.
According to the invention, the products are clamped down on a supporting element by using a vacume, and said supporting element and a rotating cutting blade are moved relative to each other along the intended cutting line so as to cut through the substrate, whilst a liquid is being supplied at the cutting line on either side of the substrate.
By using the method according to the invention, an effective cooling of the cutting blade on either side of the substrate can be effected, which has a positive influence on the working life of the cutting blade. In addition, the supply of a sufficient amount of liquid makes it possible for saving dust and any other fouling material to be washed off while the products are being separated from each other, so that it will not be necessary to clean the products after they have been separated from each other.
A method for clamping down products on a supporting element by using a sub-atmospheric pressure with a view to cutting the substrate through so as to separate the products from each other is known per se. The connecting ends face towards the substrate thereby. The construction must be such that each product to be cut out is supported all around by an edge portion which is present between the cut to be formed and the connecting ends.
According to another aspect of the invention, the products are clamped down on the supporting element on the side of the products remote from the connecting ends, so that the connecting ends can remain in sight, whilst the products can be clamped down on the at least substantially flat surface of the chip-loaded substrate. An advantage of this is the fact that it is possible to move the cutting blade closely past the connecting ends of a product, as a result of which the spacing between the products can be reduced.
A simple and efficient device for carrying out the above method is obtained when the device comprises a cutting blade to be rotated about an axis of rotation and a supporting element which is provided with spaced-apart suction cups and lines connected thereto for generating a sub-atmospheric pressure on the side of the suction cups remote from said supporting element and with lines for supplying a liquid between said suction cups.
Preferably, said supporting element is thereby fixed to a manipulator, by means of which said supporting element can be moved in desired directions relative to the cutting blade.
The invention will be explained in more detail hereafter with reference to the accompanying figures.